Range finder and height finder



June a, 1924. 1,49 ,253

A. BARR ET AL RANGE FINDER AND HEIGHT FINDER Filed Aug. 16. 1921 Patented June 3, 192 2.

STATES ATENT OFFICE.

ARCHIBALD BARR AND WILLIAM STROUD, OF ANNIESLAND, GLASGOW, SCOTLAND, ASSIGNORS TO BARB.- AND STRO'UD, LIMITED, 013 GLASGOW, SCOTLAND.

RANGE FINDER AND HEIGHT FINDER.

Serial No. 492,867.

(GRANTED UNDER THE PROVISIONSOF THE ACT OF MARCH 3, 1921, 41 STAT. L, 1313.)

To all whom it may concern:

Be it known that we, ARoHinALD BARR and WILLIAM STROUD, subjects of the King of Great Britain and Ireland, and both of Caxton Street, Anniesland, Glasgow, Scotland, have invented new and useful Improvements in Range Finders and Height Finders (which has been patented in Great Britain, No. 129,881, dated October 12, 1918), of which the following is a specification.

Our invention relates to rangefinders and heightfinders and like instruments working on the principle of triangulation from a short self-contained base, and in which the operation of taking an observation involves the translation of a deflecting prism along the beam of light from an objective to the eyepiece prism combination. For simplicity we may refer in what follows to such instruments as rangefinders.

The object of our invention is to provide improved means for carrying and operating those parts of the mechanism of a rangefinder, heightfinder, or the like, which are moved in the process of taking a range or height or other like observation so that forces applied to those parts will not produce bending or twisting of the frame carrying the fixed optical parts.

In rangefinders of the kind referred to, it has been customary to support the internal parts of the operating mechanism on the frame carrying the objectives and eyepiece prisms and to carry the working head or other external working part to which forces are applied in the operation of the instrument from an outer tube or case and to provide a flexible connection between these external and internal parts so as to minimize the effect of the forces applied from without in producing distortion of the inner frame.

According to the present invention the internal operating partsof the rang-efinder are carried on'a'" frame independent of the frzjrme carrying the fixed optical parts. This frame carrying the operating parts (which we may call the mechanism frame) is supported from the outer tube and when necessary members of it project through clearing apertures in the frame carrying the fixed optical parts (which we may refer to as the optical frame).

The mechanism frame may comprise guides for the deflecting prism and supports for the screw, rack or other gear for moving the deflecting prism. These parts will usually be inside the optical frame and members of the mechanism frame may project through apertures in the optical frame, (so arranged that the two frames do not touch each other), and be secured to the outer tube of the instrument. The working head or other external part to which forces are directly applied may then be connected mechanically to the internal operating parts without the intervention of a flexible coupling.

A like construction may be provided for the support and operation of elements provided for the adjustment of the rangefinder.

The invention is specifically valuable inl the case of rangefinders or heightfinders which are to work upon objects at different angular elevations. In such cases if the internal operating mechanism is attached to the optical frame the movable parts will have an effect in bending the optical frame in the plane of triangulation to an extent varying with the position of the moving parts-such as the deflecting prism and its mounting-in the optical frame and with the inclination of the plane of observation to the horizontal. By supporting the moving parts ,on a mechanism frame independent of the optical frame, the chief cause of such variation is. eliminated. The optical frame can then be so supported and balanced that no sensible error is produced by the varying direction of gravity relatively to the plane of triangulation and the adjustment of this balance will not be altered by movements of the operating internal parts.

The accompanying drawings show one way in which the desired result may be attained.

Figure 1 is a transverse section and Figure 2 a portion of a' longitudinal section of an instrument embodying the present invention.

Fig. 3 is a longitudinal section illustrating a portion of the same instrument showing fixed optical parts.

The instrument to which the drawings refer is a rangefinder, comprising, as indicated at Figure 3, end reflectors A, one at each end of the instrument, one end only dare of the instrument is shown the illustrattion," twdobjectives. B, an eyepiece prisms system C and eyepiece D. The objectives B are. situa ed each twe n an nd, eflec r. A and ept sms sy t m. ens be ween ea- The operating portion of the instrument consists of a deviating prism 1 which is traversed by the beam of light from an objective situated at oneend of the optical e, n. F ur 2, h lQW l d w th e piece 'pri'sm system C; see Figu es; in" a Well known manner.

"is the ube at the n trum nt and Y11 h'einner tube 1r joptical fraine of the ns, uine'nt. The optical frame'issupposed t,o carried (as is customary) from the outer tube by bearings so constructed'and arranged that forces applied "tothefouter tube in" the operation of the instrument'do not sensibly bend or distortthe optical frame.

"1' i'sth'e defiectingfprism guided,"in the case shown, by' 'a tubular entensionfl sliding on a rod 3, and prevented from rotating .aboutthe red 3103 being forked at 4 on tola secoiidguide rod .5,

' In the case shown the deflecting pri m l is operated by means of;a rack ,Gdriv "by a .tdot dwhe'el 7 tliespi'iid-le of which may berotai'ed by a working head 8, or 8111 repre a wheel;receiving'its ,i'njotioufroiii ar, tlie iiatuige of which is not matel ll to the present invention. 'lfthe'f part ,8 isnot enclosed in any casing, the opening 'i'nihe outer tube 14.- rl roughwvhicli its shaft or shafts and bearingpasses majflhe closed in any suitable manner.

In other cases thedefiecting prism ,l may be operated means of a semanvin any other suitable manner,

The guide-rods3 and5 are supported from two brackets orcross pieces 9,10, which are supported within andfniay be attached to the outer-tube 14. The brackets .9'and 10'ar'e also connected.togetherhyfbars 1.2.and 13, one of which, 13, carri'csthe bearing for the shaft which conveys motion from'the outside to the inner working parts. The parts 9, 10, 3, 5, 12 and 13, constitute what has been referred to as the mechanism frame. willbe seen from the drawings, the brackets 9 and 10 pass through apertures in the optical frame 11 so that they and the parts theycarry no not touch the optical frame. Forces applied to operate the deflecting prism gear therefore do not affect the opticaliframe nor does the Weight of the mechanism, frame or of deflecting prism and. parts that move with it affect the optical frame however the instrument may be placed. In like manner the scaleifan internal one is usedand the adjusting gear may be carried on the same or on anaddition al mechanism frame. By these means, the communication of motion to the operating mechanism of the range finder'from parts outside, without affecting on a mechanism frame or frames which have no contact with the optical fame carrying the objectives and eyepiece prisms.

lVe claim:-

1. A self contained base single observer r angefinde r, heightfinder, or likeinstriunent, comprising, an outer case, a frame located within the outer case on" which objectives and "eyepiece prism system are mounted, a

structure fixed to the outer case and clear of-th e frame on which structure is mounted an optical 'part located within the frameand which is required to he moved in the operation of determining a range or height, said frame havingapertures and said structure l avingniemliiers which extend through said apertures, for the purposes set forth.

' 2. A self contained base single observer rangefinder, heightfinder, or like instrument, co n'pi'sing an outer case. a frame located within outer ase on which objectives and eyepiece prism system are mounted, a 100 structurelined to the outer case and clear ot the frame, a longitudinal guide carried by said structure, optical parts located within the frame and which are required to be moved iu'the" operation of determining a rangeor height mounted to slide-upousaid guide, said frame having apertures and said structure having members which extend. through said apertures, forthe purposessct forth.

ABCHIBALD BARR. WILLIAM 

